Improve the real or perceived speed of the site, or monitor performance metrics.
Yac is a shared and lockless memory user data cache for PHP.
it can be used to replace APC or local memcached.
Integration with DropShark monitoring, trending, and alerts service.
This module was created primarily to address issues related to the cache_form table in Drupal.
FWIW, superseded by IO module.
AJAX Include Pattern for Modular Content.